JP2020039850A - Ophthalmologic apparatus - Google Patents

Abstract

To provide an ophthalmologic apparatus capable of automatically and accurately examining strabismus and phoria of the eye to be tested.SOLUTION: An ophthalmologic apparatus 10 has: a visual axis movement detection part 27c detecting a movement of a visual axis of at least either the right eye to be tested or the left eye to be tested from anterior ocular images of the right eye to be tested and the left eye to be tested acquired by an imaging device 31g in the state that a fixed optotype is presented by a display 32a of an optotype projection system 32; a fixed optotype movement control part 27d moving the fixed optotype on the basis of the movement of the visual axis detected by the visual axis movement detection part 27c; and a visual axis calculation part 27e calculating a visual axis of either the right eye to be tested or the left eye to be tested on the basis of a movement amount of the fixed optotype moved by the fixed optotype movement control part 27d.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an ophthalmologic apparatus capable of inspecting a strabismus of an eye to be examined.

  2. Description of the Related Art Conventionally, it has been known that correction of strabismus and oblique position is performed using glasses (prism glasses). Further, the examination of the strabismus and the oblique position is manually performed by an ophthalmologist, a vision trainer, or a clerk of an optician by a manual examination requiring skill and experience.

Japanese Patent No. 5011144

  However, manual examination of strabismus and oblique position is difficult to perform in a spectacle shop with few staff members having ophthalmological expertise because the results are easily affected by the knowledge and skill of the examiner.

  On the other hand, it is known that uncorrection of strabismus and obliqueness is known to contribute to eyestrain. The potential demand to do is high.

  It should be noted that an ophthalmologic measurement device has been proposed which detects the direction of the line of sight of the eye when the visible light is transmitted to the eye or when the visible light is transmitted after the visible light is blocked (Patent Document 1). Reference), even with such a device, it was difficult to precisely measure the squint and oblique position of the eye to be examined.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ophthalmologic apparatus capable of automatically and precisely inspecting a squint and an oblique position of a subject's eye.

  In order to achieve the object, the ophthalmologic apparatus of the present invention includes a pair of measurement heads each storing a measurement optical system that acquires eye information of the right eye or the left eye of the subject, and a measurement optical system. An image acquisition unit that is provided, and acquires an anterior eye image on the optical axis of the measurement optical system of the right eye and the left eye; and a line of sight of at least one of the right eye and the left eye that is provided in the measurement optical system. A target projection system that presents a fixation target for performing right fixation to the right subject's eye and the left subject's eye, and a right subject's eye and a left subject's eye acquired by the image acquisition unit in a state where the fixation target is presented. From the anterior segment image, a visual axis movement detecting unit that detects movement of at least one visual axis of the right eye or the left eye, and a fixation target based on the visual axis movement detected by the visual axis movement detecting unit. Fixation target movement control unit that moves the object in the direction that intersects the optical axis, and the amount of movement of the fixation target Based and having a visual axis calculation unit for calculating a visual axis of the right eye to be examined or left eye E.

  In the ophthalmologic apparatus of the present invention thus configured, the fixation target movement control unit moves the fixation target in a direction intersecting the optical axis based on the movement of the visual axis detected by the visual axis movement detection unit, The visual axis calculation unit calculates the visual axis of the right eye or the left eye based on the amount of movement of the fixation target moved by the fixation target movement control unit.

  Therefore, according to the ophthalmologic apparatus of the present invention, it is possible to automatically and precisely perform the examination of the perspective and the oblique position of the eye to be inspected.

FIG. 1 is a perspective view illustrating an overall configuration of an ophthalmologic apparatus according to an embodiment. FIG. 2 is a diagram illustrating a detailed configuration of a measurement optical system for the right eye of the ophthalmologic apparatus according to the present embodiment. It is a perspective view showing an example of a rotary prism used for the ophthalmologic apparatus which is this embodiment. FIG. 1 is a block diagram illustrating an overall configuration of an ophthalmologic apparatus according to an embodiment. FIG. 3 is a block diagram illustrating a configuration of a control system of the ophthalmologic apparatus according to the present embodiment. FIG. 3 is a schematic diagram illustrating a relationship between a visual axis and a pupil axis of an eye to be examined. FIG. 3 is a diagram illustrating a point image formed inside an eye to be examined by a point light source. It is a figure which shows the type of perspective. FIG. 5 is a diagram illustrating a pupil center and a position of corneal reflection in an anterior segment image acquired by an ophthalmologic apparatus. It is a figure for explaining the schematic diagram showing the position of a pupil center and a corneal reflex. It is a figure which shows the relationship between the rotation of an eyeball centering on an eyeball rotation point, and the position of a corneal reflection. FIG. 4 is a diagram illustrating a relationship between the rotation of the eyeball about the eyeball rotation point and the position of the center of the pupil. FIG. 3 is a diagram for explaining a rotation state of a measurement head by a measurement head control unit. 5 is a flowchart for explaining the operation of the ophthalmologic apparatus according to the present embodiment. FIG. 4 is a diagram illustrating an example of a relationship between a fixation target presented by the ophthalmologic apparatus according to the present embodiment and eye movement of the subject's eye. FIG. 9 is a diagram illustrating another example of the relationship between the fixation target presented by the ophthalmologic apparatus according to the present embodiment and the eyeball movement of the subject's eye. It is a figure which shows the other example of the relationship between the fixation target presented by the ophthalmologic apparatus which is this Embodiment, and the movement of the eyeball of an eye to be examined. It is a figure which shows the other example of the relationship between the fixation target presented by the ophthalmologic apparatus which is this Embodiment, and the movement of the eyeball of an eye to be examined. It is a figure which shows the other example of the relationship between the fixation target presented by the ophthalmologic apparatus which is this Embodiment, and the movement of the eyeball of an eye to be examined. FIG. 5 is a diagram illustrating an example of a screen displayed on a display unit of the ophthalmologic apparatus according to the present embodiment.

Hereinafter, the ophthalmologic apparatus according to the present embodiment will be described with reference to FIGS. First, the overall configuration of the ophthalmologic apparatus 10 will be described.
(Overall configuration of ophthalmic device)

  As shown in FIG. 1, the ophthalmologic apparatus 10 includes a base 11, an optometry table 12, a support 13, an arm 14, a drive mechanism (drive unit) 15, and a pair of measurement heads 16. In the ophthalmologic apparatus 10, the subject facing the optometry table 12 acquires information on the subject's eye to be examined in a state where the subject applies his forehead to the forehead contact part 17 provided between the two measurement heads 16. . As shown in FIG. 1 throughout this specification, the X axis, the Y axis, and the Z axis are taken, and when viewed from the subject, the left-right direction is the X direction, the up-down direction (vertical direction) is the Y direction, and the X direction is the X direction. A direction orthogonal to the Y direction (the depth direction of the measuring head 16) is defined as a Z direction.

  The optometry table 12 is a desk on which a display unit / examiner controller (hereinafter, simply referred to as an examiner controller 25) 25 and a controller 26 for the examinee, which are described later, are placed, and those used for optometry are placed. And is supported by the base 11. The optometry table 12 may be supported by the base 11 so that the position (height position) in the Y direction can be adjusted.

  The column 13 is supported by the base 11 so as to extend in the Y direction at the rear end of the optometry table 12, and an arm 14 is provided at the tip.

  The arm 14 suspends both measurement heads 16 on the optometry table 12 via the drive mechanism 15, and extends in the Z direction from the support 13 to the near side. The arm 14 is movable in the Y direction with respect to the support 13. Note that the arm 14 may be movable in the X direction and the Z direction with respect to the support 13. A pair of measuring heads 16 are supported at the tip of the arm 14 by being suspended by a driving mechanism 15.

  The measurement heads 16 are provided in pairs to individually correspond to the left and right eyes to be examined of the subject. Hereinafter, when individually described, they are referred to as a left-eye measurement head 16L and a right-eye measurement head 16R. . The measurement head 16L for the left eye acquires information on the eye to be examined on the left side of the subject, and the measurement head 16R for the right eye acquires information on the eye to be examined on the right side of the subject. The measurement head 16L for the left eye and the measurement head 16R for the right eye are configured to be plane-symmetric with respect to a vertical plane located between them in the X direction.

  Each of the measuring heads 16 is provided with a mirror 18 serving as a deflecting member, and information of the corresponding eye to be inspected is acquired through the mirror 18 by a measuring optical system 21 described later.

  Each measurement head 16 is provided with a measurement optical system 21 for acquiring eye information of the eye to be inspected (a right-eye measurement optical system 21R and a left-eye measurement optical system 21L when individually described). The detailed configuration of the measurement optical system 21 will be described later.

  Both measuring heads 16 are movably suspended by a drive mechanism 15 provided on a base 19 suspended from the tip of the arm 14. In the present embodiment, as shown in FIG. 4, the drive mechanism 15 includes a left-eye vertical drive unit 22L, a left-eye horizontal drive unit 23L, and a left-eye rotation drive unit 24L corresponding to the left-eye measurement head 16L. And a right-eye vertical drive unit 22R, a right-eye horizontal drive unit 23R, and a right-eye rotation drive unit 24R corresponding to the right-eye measurement head 16R.

  The configuration of each drive unit corresponding to the measurement head 16L for the left eye and the configuration of each drive unit corresponding to the measurement head 16R for the right eye are plane-symmetrical with respect to a vertical plane located between them in the X direction. Therefore, when not individually described, they are simply referred to as a vertical drive unit 22, a horizontal drive unit 23, and a rotation drive unit 24 (see FIG. 4).

  As shown in FIG. 4, the vertical drive unit 22 is provided between the base unit 19 and the horizontal drive unit 23, and moves the horizontal drive unit 23 in the Y direction (vertical direction) with respect to the base unit 19. The horizontal drive unit 23 is provided between the vertical drive unit 22 and the rotation drive unit 24, and moves the rotation drive unit 24 in the X direction and the Z direction (horizontal direction) with respect to the vertical drive unit 22.

  The vertical drive unit 22 and the horizontal drive unit 23 are provided with an actuator that generates a driving force such as a pulse motor, and a transmission mechanism that transmits the driving force such as a combination of gears or a rack and pinion. It is composed. The horizontal driving unit 23 can be easily configured and can easily control the movement in the horizontal direction, for example, by providing a combination of an actuator and a transmission mechanism individually in the X direction and the Z direction.

  The rotation drive unit 24 moves the corresponding measurement head 16 with respect to the horizontal drive unit 23 to a pair of eyeball rotation axes extending in the vertical direction (Y direction) and the horizontal direction (X direction) through the eyeball rotation point of the corresponding eye to be examined. Rotate each around. The rotation drive unit 24 includes, for example, a configuration in which a transmission mechanism that receives a driving force from an actuator moves along an arc-shaped guide groove. The measurement head 16 is rotated about the rotation axis of the eyeball.

  In addition, the rotation drive unit 24 supports the measurement head 16 so as to be rotatable around a rotation axis provided on the rotation drive unit 24 and cooperates with the horizontal drive unit 23 to rotate while changing the position where the measurement head 16 is supported. Good.

  Thereby, the drive mechanism 15 can move the measuring heads 16 individually or in conjunction with each other in the X direction, the Y direction, and the Z direction, and can rotate the measurement head 16 around the eyeball rotation axis of the eye to be examined. .

  As shown in FIGS. 1 and 5, the base 11 is provided with a control unit 27 that controls each unit of the ophthalmologic apparatus 10. The control unit 27 has a communication unit 27b capable of short-range wireless communication with the examiner controller 25.

  The examiner's controller 25 is an information processing device having a communication unit 25d capable of short-range communication with the control unit 27, such as a tablet terminal or a smartphone. The examiner controller 25 is used by the examiner to operate the ophthalmologic apparatus 10. The examiner controller 25 causes a predetermined screen to be displayed on the display surface 25a based on the display control signal sent from the control unit 27. A touch panel type input unit 25c is provided on the display surface 25a. The operation input signal received by the input unit 25c is sent to the control unit 27 via the communication unit 25d.

  In the ophthalmologic apparatus 10 of the present embodiment, the controller 25 for the examiner is configured to be portable, and may be operated in a state where the controller 25 is arranged on the table 12 for the examiner. It may be operated.

  The functional configuration of the ophthalmologic apparatus 10 will be described later in detail.

(Optical system of ophthalmic device)
FIG. 2 is a diagram illustrating a detailed configuration of the measurement optical system 21R for the right eye in the ophthalmologic apparatus according to the present embodiment. Note that the configuration of the left-eye measurement optical system 21L is the same as that of the right-eye measurement optical system 21R, and a description thereof will be omitted, and only the right-eye measurement optical system 21R will be described.

  The measurement optical system 21R for the right eye includes an observation system 31, a target projection system 32, an eye refractive power measurement system 33, an alignment system 35, an alignment system 36, and a kerato system 37, as shown in FIG.

  The observation system 31 observes the anterior segment of the eye E, the target projection system 32 presents a target to the eye E, and the eye refractive power measurement system 33 measures the eye refractive power.

  In the present embodiment, the eye refractive power measurement system 33 has a function of projecting a predetermined measurement pattern on the fundus oculi Ef of the eye E and a function of detecting an image of the measurement pattern projected on the fundus oculi Ef.

  The alignment system 35 and the alignment system 36 perform positioning (alignment) of the optical system with respect to the eye E to be inspected, and the alignment system 36 is arranged in the direction (the front-back direction) along the optical axis of the observation system 31 and the alignment system 36 is adjusted to the optical axis. Alignment is performed in directions perpendicular to (vertical and horizontal).

  The observation system 31 includes an objective lens 31a, a dichroic filter 31b, a half mirror 31c, a relay lens 31d, a dichroic filter 31e, an imaging lens 31f, and an image sensor (CCD: image acquisition unit) 31g.

  In the observation system 31, the light beam reflected by the eye E (anterior eye) is imaged on the image sensor 31g by the imaging lens 31f via the objective lens 31a. As a result, an anterior segment image E ′ is formed on the image sensor 31g, on which a keratling light beam, a light beam of the alignment light source 35a, and a light beam (bright spot image Br) of the alignment light source 36a are projected (projected). You. The image sensor 31g of the observation system 31 captures the anterior segment image E '. The control unit 27 displays an anterior ocular segment image E ′ and the like based on the image signal output from the image sensor 31g on the display surface 25a of the examiner controller 25.

  A kerato system 37 is provided in front of the objective lens 31a. The kerato system 37 includes a kerato plate 37a and a kerato ring light source 37b. The kerato plate 37a has a plate shape provided with a slit concentric with the optical axis of the observation system 31, and is provided near the objective lens 31a. The kerato ring light source 37b is provided in accordance with the slit of the kerato plate 37a.

  In the kerato-system 37, the luminous flux from the lit kerato-ring light source 37b passes through the slit of the kerato-plate 37a, so that the kerato-ring luminous flux (ring for measuring the corneal curvature) for the eye E (cornea Ec) is measured. The target is projected (projected). The kerattling light beam is reflected by the cornea Ec of the eye E to be examined, and is imaged on the image sensor 31g by the observation system 31. As a result, the image sensor 31g detects (receives) an image (image) of the ring-shaped kerat ring light beam, and the control unit 27 causes the display surface 25a to display the image of the measurement pattern, and the image (image sensor 31g) The corneal shape (radius of curvature) is measured by a well-known method based on the image signal from).

  In the present embodiment, an example (keratous system 37) is shown as a corneal shape measuring system in which a ring slit is about 1 to 3 times and a keratoplate 37a that measures curvature near the center of the cornea is used. As long as the corneal shape is measured, a platid plate having multiple rings and capable of measuring the shape of the entire cornea may be used, other configurations may be used, and the configuration is not limited to the configuration of the present embodiment.

  An alignment system 35 is provided behind the kerato system 37 (kerato plate 37a). The alignment system 35 has a pair of alignment light sources 35a and a projection lens 35b, converts the light flux from each alignment light source 35a into a parallel light flux with each projection lens 35b, and passes the cornea of the eye E through an alignment hole provided in the kerato plate 37a. The parallel light beam is projected (projected) on Ec.

  The control unit 27 or the examiner moves the measuring head 16 in the front-rear direction based on the bright spot (bright spot image) projected (projected) on the cornea Ec, so that the direction along the optical axis of the observation system 31 ( Alignment in the front-back direction). The alignment in the front-back direction is performed by adjusting the position of the measuring head 16 so that the ratio of the distance between two point images by the alignment light source 35a on the image sensor 31g and the diameter of the kerattling image is within a predetermined range.

  Here, the controller 27 may calculate the amount of alignment deviation from the ratio and display the amount of alignment deviation on the display surface 25a. Note that the alignment in the front-rear direction may be performed by adjusting the position of the measuring head 16 so that the bright spot image Br is focused by the alignment light source 36a described later.

  The observation system 31 is provided with an alignment system 36. The alignment system 36 has an alignment light source 36a and a projection lens 36b, and shares the half mirror 31c, the dichroic filter 31b, and the objective lens 31a with the observation system 31.

The alignment system 36 projects (projects) the light beam from the alignment light source 36a as a parallel light beam through the objective lens 31a onto the cornea Ec of the eye E to be inspected. Parallel beam K which is projected onto the cornea Ec of the eye E from the alignment system 36, a substantially intermediate position of the corneal apex Ept and the corneal curvature center R _0, to form a bright spot Q alignment light (see FIG. 7). The control unit 27 or the examiner moves the measuring head 16 in the front-rear direction based on the image (bright spot image) Br of the bright spot Q projected (projected) on the cornea Ec, so that the optical axis of the observation system 31 is adjusted. Alignment is performed in the direction (vertical direction, horizontal direction) orthogonal to.

  At this time, the control unit 27 causes the display surface 25a to display an alignment mark AL serving as a guide of the alignment mark, in addition to the anterior eye image E 'on which the bright spot image Br is formed. The control unit 27 may be configured to control the measurement to be started when the alignment is completed.

  The alignment light source 36a is a light emitting diode that emits infrared light (for example, 940 nm) in order to prevent the subject from visually recognizing the alignment light source 36a during the alignment operation by the alignment system 36.

  The optotype projection system 32 is an optical system that projects an optotype to fixate and cloud the eye to be inspected E and presents it to the fundus oculi Ef. The target projection system 32 includes a display (target display unit) 32a, rotary prisms 32A and 32B, an imaging lens 32b, a moving lens 32c, a relay lens 32d, a field lens 32f, a mirror 32h, and a dichroic filter 32i. The filter 31b and the objective lens 31a are shared with the observation system 31.

  The display 32a displays a landscape chart that performs fixation and fogging, a Landolt ring, an E-character optotype, an optometry optotype, and the like when performing an objective test and a subjective test.

  The display 32a can be formed of an EL (electroluminescence) or a liquid crystal display (LCD), and displays an arbitrary image under the control of the control unit 27. The display 32a is provided movably along the optical axis at a position conjugate with the fundus oculi Ef of the eye E on the optical path of the optotype projection system 32.

  The rotary prisms 32A and 32B are used to adjust the prism power and the prism base direction in the oblique inspection. The rotary prisms 32A and 32B are independently rotated by driving a pulse motor or the like (not shown). As shown in FIG. 3, when the rotary prisms 32A and 32B are rotated in opposite directions, the prism power is continuously changed, and when they are integrally rotated in the same direction, the prism base direction is continuously changed. .

  The movable lens 32c is driven forward and backward along the optical axis by a drive motor (not shown). By moving the moving lens 32c to the eye E, the refractive power can be displaced to the minus side, and by moving the moving lens 32c away from the eye E, the refractive power can be moved to the positive side. Can be displaced. Therefore, the presenting distance of the optotype displayed on the display 32a can be changed by moving the moving lens 32c forward and backward, that is, the presenting position of the optotype image can be changed, and the eye E to be examined can be fixed and fogged. it can.

  The eye-refractive-power measuring system 33 projects a ring-shaped luminous flux projection system 33A that projects a ring-shaped measurement pattern onto the fundus oculi Ef of the eye E, and a ring that detects (receives) reflected light of the ring-shaped measurement pattern from the fundus oculi Ef. It has a linear light beam receiving system 33B.

  The ring-shaped light beam projection system 33A has a reflex light source unit 33a, a relay lens 33b, a pupil ring stop 33c, a field lens 33d, a perforated prism 33e, and a rotary prism 33f, and shares a dichroic filter 32i with the target projection system 32. Then, the dichroic filter 31b and the objective lens 31a are shared with the observation system 31. The reflex light source unit 33a includes, for example, a reflex measurement light source 33g for reflex measurement using an LED, a collimator lens 33h, a conical prism 33i, and a ring pattern forming plate 33j. It can move integrally on the optical axis of the measurement system 33.

  The ring-shaped light beam receiving system 33B includes a hole 33p of a perforated prism 33e, a field lens 33q, a reflection mirror 33r, a relay lens 33s, a focusing lens 33t, and a reflection mirror 33u, and an objective lens 31a, a dichroic filter 31b, and a dichroic. The filter 31e, the imaging lens 31f, and the image sensor 31g are shared with the observation system 31, the dichroic filter 32i is shared with the target projection system 32, and the rotary prism 33f and the perforated prism 33e are shared with the ring light beam projection system 33A. .

  Next, the operation in the eye refractive power measurement mode will be described. The control unit 27 turns on the reflex measurement light source 33g, and moves the reflex light source unit 33a of the ring-shaped light beam projection system 33A and the focusing lens 33t of the ring-shaped light beam reception system 33B in the optical axis direction. In the ring-shaped light beam projection system 33A, the reflex light source unit 33a emits a ring-shaped measurement pattern, and advances the measurement pattern to the perforated prism 33e through the relay lens 33b, the pupil ring stop 33c, and the field lens 33d. The light is reflected by the reflection surface 33v and guided to the dichroic filter 32i via the rotary prism 33f. In the ring light beam projection system 33A, the measurement pattern is guided to the objective lens 31a through the dichroic filter 32i and the dichroic filter 31b, thereby projecting the ring measurement pattern on the fundus oculi Ef of the eye E to be inspected.

  In the ring-shaped light beam receiving system 33B, the ring-shaped measurement pattern formed on the fundus oculi Ef is condensed by the objective lens 31a, and is passed through the dichroic filter 31b, the dichroic filter 32i and the rotary prism 33f to the hole 33p of the perforated prism 33e. Let go. In the ring-shaped light beam receiving system 33B, the measurement pattern passes through the field lens 33q, the reflection mirror 33r, the relay lens 33s, the focusing lens 33t, the reflection mirror 33u, the dichroic filter 31e, and the imaging lens 31f, and is transmitted to the image sensor 31g. Make an image. Thereby, the image sensor 31g detects the image of the ring-shaped measurement pattern, and the controller 27 displays the image of the measurement pattern on the display surface 25a, and based on the image signal from the image (image sensor 31g), The spherical power, cylindrical power, and axis angle as eye refractive power are measured by a known method.

  In the eye-refractive-power measurement mode, the control unit 27 causes the display 32a to display a fixed fixation target in the target projection system 32. The luminous flux from the display 32a passes through rotary prisms 32A and 32B, an imaging lens 32b, a moving lens 32c, a relay lens 32d, a field lens 32f, a mirror 32h, a dichroic filter 32i, a dichroic filter 31b, and an objective lens 31a. Is projected (projected) on the fundus oculi Ef. The examiner or the control unit 27 performs the alignment while fixing the presented fixed fixation target to the subject, and based on the result of the provisional measurement of the eye refractive power (ref), moves to the far point of the eye E to be examined. After moving the moving lens 32c, the state is further changed to a cloudy state, and the eye refractive power at the time of accommodation suspension is measured.

  The configuration of the eye refractive power measurement system 33, the alignment system 35, the alignment system 36, the kerato system 37, and the like, and the principles of measurement of the eye refractive power (ref), subjective examination, and corneal shape (kerato) are known. Detailed description is omitted.

(Control system for ophthalmic equipment)
The functional configuration of the ophthalmologic apparatus 10 according to the present embodiment will be described with reference to FIG. The control unit 27 includes, in addition to the measurement optical system 21 described above, the vertical drive unit 22, the horizontal drive unit 23, and the rotation drive unit 24 as the drive mechanism 15, an examiner controller 25 and a subject controller 26. And the storage unit 28 are connected.

  The examiner controller 25 has a display unit 25b that displays a screen on the display surface 25a based on the display control signal transmitted from the control unit 27. On the display surface 25a of the display unit 25b, a touch panel type input unit 25c is provided. The display unit 25b displays a schematic diagram showing the pupil center and the position of the corneal reflection in the anterior ocular segment image E '. In addition, the display unit 25b displays a cross-sectional view in which the visual axis and the optical axis are written on the horizontal cross sections of the right eye and the left eye. Further, the display unit 25b displays the distance between the position of the fixation target presented in front of the right eye and the left eye and the right eye or the left eye. Details of the screen displayed by the display unit 25b will be described later.

  The examiner's controller 25 and the control unit 27 are capable of short-range wireless communication by communication units 25d and 27b provided in the examiner's controller 25 and the control unit 27, respectively.

  The subject controller 26 is used by the subject to respond when acquiring various kinds of eye information of the subject's eye. The subject controller 26 includes an input device such as a keyboard, a mouse, and a joystick. The control unit 27 is connected to the subject controller 26 via a wired or wireless communication path.

  The control unit 27 expands a program stored in the connected storage unit 28 or the built-in internal memory 27a on, for example, a RAM, and appropriately operates the controller 25 for the examiner or the controller 26 for the subject, The operation of the ophthalmologic apparatus 10 is generally controlled, and a visual axis movement detection unit 27c, a fixation target movement control unit 27d, a visual axis calculation unit 27e, a shielding unit control unit 27f, a pupil center detection unit 27g, and a corneal reflection, which will be described later. Functions as the position detection unit 27h. In the present embodiment, the internal memory 27a is configured by a RAM or the like, and the storage unit 28 is configured by a ROM, an EEPROM, or the like.

  The visual axis movement detection unit 27c is configured to display the right subject's eye and the left subject acquired by the image acquisition unit (imaging device: CCD 31g) while the fixation target is presented by the target display unit (display 32a) of the target projection system 32. The movement of the visual axis of at least one of the right eye and the left eye is detected from the anterior segment image E ′ of the optometry.

  The fixation target movement control unit 27d moves the fixation target in a direction intersecting the optical axis based on the movement of the visual axis detected by the visual axis movement detection unit 27c. As an example, the fixation target movement control unit 27d moves the fixation target displayed on the display 32a on the display 32a and / or rotates the measurement head 16 to move the fixation target. Further, the fixation target movement control unit 27d moves the fixation target by changing the prism power given by the rotary prisms 32A and 32B of the target projection system 32.

  The visual axis calculation unit 27e calculates the visual axis of the right eye or the left eye based on the amount of movement of the fixation target by the fixation target movement control unit 27d. Further, the visual axis calculation unit 27e calculates the prism base direction and the prism power of the right eye and the left eye based on the calculated visual axes of the right eye and the left eye.

  The shielding unit control unit 27f causes the shielding unit 32j of the target projection system 32 to block the presentation of the fixation target to the right or left subject's eye, and to block the presentation of the fixation target after blocking the presentation of the fixation target. The shielding of the presentation of the fixation target by 32j is stopped. Then, the visual axis movement detection unit 27c is configured to block at least one of the right eye and the left eye after blocking the presentation of the fixation target by the shielding unit 32j or stopping the blocking of the presentation of the fixation target by the shielding unit 32j. Detect axis movement.

  The pupil center detection unit 27g detects the pupil centers of the right eye and the left eye from the anterior eye images E ′ of the right eye and the left eye obtained by the imaging device 31g of the observation system 31. The corneal reflection position detection unit 27h performs a right luminous point Q obtained by forming an image of the parallel light flux K (see FIG. 7) from the alignment light source 36a of the alignment system 36 in the right eye and the left eye. The corneal reflection of the subject's eye and the left subject's eye, that is, the position of the bright spot image Br that is the image of the bright spot Q is detected. As shown in FIG. 7, when the parallel light flux K from the alignment light source 36a is incident on the eyeball, a spot-like image (Purkinje image) is formed at a position Q (half the radius of curvature r of the cornea, r / 2) inside the cornea Ec, That is, corneal reflection Br is formed. Then, the visual axis calculation unit 27e verifies the calculated visual axis based on the pupil center and the corneal reflection position detected by the pupil center detection unit 27g and the corneal reflection position detection unit 27h.

  Further, in the ophthalmologic apparatus 10 according to the present embodiment, the anterior eye images EL ′ and ER ′ of the left eye EL and the right eye ER are displayed on the display surface 25a of the display unit 25b (see FIG. 15). . For this reason, by visually recognizing these, the examiner can grasp, for example, the cause of the failure of the alignment or the inspection. In other words, as a cause of poor alignment or the like, for example, fixation is not possible, binocular vision is not possible, there is strabismus or obliqueness, there is ptosis, there is suppression, there is pupil miosis, The part is inclined. By visually recognizing the anterior eye images EL ′ and ER ′ of the left eye EL and the right eye ER displayed on the display surface 25a during the alignment or the like, the examiner can clearly determine the cause of the inability to perform the alignment or the like. It becomes possible to grasp. Then, corrective measures can be taken promptly by correcting the position of the head or calling attention to the subject, and the success rate of realignment and the like can be improved.

  The function realizing means of the control unit 27 will be described later in detail.

  As already described in detail, the measurement optical system 21 includes an observation system 31, a target projection system 32, an eye refractive power measurement system 33, an alignment system 35, an alignment system 36, and a kerato system 37.

  The optotype projection system 32 has a shielding unit 32j that shields the fixation target from being presented to the eye E that does not fixate on the fixation target in a state where the fixation target is presented by the display 32a. In the ophthalmologic apparatus 10 according to the present embodiment, the optotype projection system 32 presents a fixation target on its display 32a, and thus turns off the display 32a on which the fixation target is presented (turns off the display). Accordingly, it is possible to reproduce a state equivalent to a state in which the shielding member is arranged on the front surface of the eye E to be inspected. Therefore, the shielding unit 32j turns off the display 32a of the optotype projection system 32 based on an instruction from the control unit 27 or the like.

(principle)
Next, the measurement principle of the ophthalmologic apparatus 10 according to the present embodiment will be described with reference to FIGS. 6 to 13 and FIGS.

  The ophthalmologic apparatus 10 according to the present embodiment is an apparatus that quantitatively measures the strabismus of the eye E to be inspected. Here, the term “strabismus” means that the line of sight of the right eye and the left eye is directed to different places. In the case of the eye E having no squint, when the common eye is fixed by the right eye and the left eye, the line of sight of the right eye and the left eye is located at a common place (fixation target) substantially in front. Heading. However, when the eye E is oblique, the line of sight of one of the right eye and the left eye does not face the fixation target, and therefore, the line of sight of the eye E goes to a different place. In the ophthalmologic apparatus 10 according to the present embodiment, an examination is performed when the line of sight of the eye E to be inspected, either the right eye or the left eye, does not face the fixation target.

  In the ophthalmologic apparatus 10 according to the present embodiment, the deviation between the visual axis VX and the optical axis of the measurement optical system 21 is obtained based on an alternative prism cover test (APCT). In the alternating prism shielding test, the subject's eyes whose eyes are directed to the fixation target by the Hirshberg method (hereinafter, this may be referred to as the fixation eye) and the eyes whose vision is not directed to the fixation target ( Hereinafter, this may be referred to as a non-fixation eye), and further, a rough shift between the visual axis VX and the optical axis of the measurement optical system 21 is grasped. After that, a prism having a prism power corresponding to the amount of displacement is arranged in front of the non-fixation eye, and then the fixation eye and the non-fixation eye are alternately shielded and the prism power is observed while observing the eye movements of both eyes. The objective quantitative test of strabismus is performed based on the prism power when the eye movements of both eyes disappear.

  Note that the fixation eye is the eye E without a squint, and the non-fixation eye can be paraphrased as the eye E with a squint. In the following description, a case where the right eye ER is the fixation eye and the left eye EL is the non-fixation eye will be described as an example.

  First, as illustrated in FIG. 15, the control unit 27 causes a fixation target to be displayed at a center position of the display 32 a of the target projection system 32 of the ophthalmologic apparatus 10. At this time, the fixation target presented to the right subject's eye ER, which is the fixation eye, and the fixation target presented to the left subject's eye EL, which is the non-fixation eye, are made different. In the example shown in FIG. 15, fixation targets in which X is displayed in the right eye ER and 位置 is displayed in the center position of the left eye EL are displayed on the displays 32 a of the respective measurement optical systems 21.

  At this time, since different fixation targets are presented to the right eye ER and the left eye EL, it is preferable that no fusion stimulation is given to the right eye ER and the left eye EL. For this reason, a rectangular fusion frame or the like is not displayed simultaneously around the fixation target.

  The quantitative examination of the strabismus using the ophthalmologic apparatus 10 according to the present embodiment can be performed at any of the near eye position and the far eye position. When performing a quantitative examination of the strabismus in the near eye position, the control unit 27 rotates the measuring heads 16R and 16L about the eye rotation axes of the right eye ER and the left eye EL by the driving mechanism 15, and the eye E Is instructed to fixate on the fixation target displayed at the fixation point PO (see FIG. 13) ahead by an examination distance (for example, 33 cm according to the Hirschberg method). Thus, the right eye ER and the left eye EL are converged, and the fixation target is gazed at.

The rotation angles of the measuring heads 16R and 16L can be obtained as follows. As shown in FIG. 13, the presentation distance (examination distance) from the left subject's eye EL (or the right subject's eye ER) to the presentation position of the fixation target is L, the interpupillary distance of the subject is PD, Assuming that half of the distance is hPD, the convergence angle の of the right eye ER or the left eye EL is given by the following equation (1).
The convergence angle Θ is the rotation angle of the measuring heads 16R, 16R.

  On the other hand, when performing a quantitative examination of the strabismus in the distant eye position, the control unit 27 rotates the measuring heads 16R and 16L by the driving mechanism 15 so that the fixation target is displayed at an optically distant position from the eye E to be examined. . In this case, the rotation angle (convergence angle Θ) of the measuring head 16 is almost zero.

  In this state, the examiner instructs the subject to fixate the fixation target with both eyes. Note that when the subject cannot visually recognize the fixation targets x and ● presented to the right eye ER and the left eye EL at the same time, the ophthalmologic apparatus 10 according to the present embodiment performs a quantitative examination of strabismus. The subsequent examination is stopped because it is not applicable.

  Next, as shown in FIG. 16A, the shielding unit control unit 27f of the control unit 27 displays the target target projection system 32 of the measurement optical system 21 that measures the left subject's eye EL, which is a non-fixated eye. 32a is turned off by the shielding unit 32j, and visible light to the left eye EL is shielded. At this time, the examiner instructs the subject to fixate the fixation target x with the right subject's eye ER, which is the fixation eye.

  The shielding of the visible light to the left subject's eye EL by the shielding part 32j prevents the left subject's eye EL from fixing the fixation target ●, so that the left subject's eye EL moves. In FIGS. 16 to 18, the movement of the eyeball of the eye E is indicated by the movement of the pupil P. In FIG. 16A, the pupil of the left subject's eye EL moves outward (leftward in the figure) due to shielding of the left subject's eye EL from visible light (pupil P1 → P2).

  Two seconds after the shielding of the visible light to the left subject's eye EL, the shielding part control part 27f of the control part 27 measures the right subject's eye ER, which is the fixation eye, as shown in FIG. The display 32a of the optotype projection system 32 of the measurement optical system 21 is turned off by the shielding unit 32j, and visible light to the right eye ER is shielded. At the same time, the shielding section control section 27f of the control section 27 turns on the display 32a to cause the left subject's eye EL to present the fixation target ●.

  In this state, the examiner instructs the subject to fixate the fixation target ● with the left subject's eye EL, which is a non-fixed eye. When the left subject's eye EL fixes the fixation target ●, the pupil of the left subject's eye EL moves inward (rightward in the figure) (pupil P2 → P3).

  Here, the right eye ER is shielded from the presentation of the fixation target x by the shielding unit 32j, but the command amounts of the left and right eye movements commanded by the cerebrum are equal according to Herring's law. The same eyeball movement instruction also reaches the right eye ER from the cerebrum as the left eye EL moves. Therefore, the pupil of the right eye ER also moves with the pupil of the left eye EL (pupil P4 → P5).

  In addition, when neither the right eye ER nor the left eye EL has a perspective (that is, a normal position), no eye movement occurs in any eye E.

  The imaging device 31g of the observation system 31 of the ophthalmologic apparatus 10 observes the eyeball movement of the left eye E by capturing the anterior eye image E ′ of the eye E. At this time, even if the display 32a is turned off by the shielding unit 32j, the imaging element 31g can observe the anterior eye image E 'of the subject's eye E, regardless of whether or not the shielding unit 32j blocks visible light. Instead, the eyeball movement of the eye E can be observed.

  Then, the shielding unit control unit 27f of the control unit 27 performs non-fixation as shown in FIG. 17B after 0.5 seconds from the shielding of the visible light to the right eye ER shown in FIG. 17A. The display 32a of the optotype projection system 32 of the measuring optical system 21 that measures the left eye E, which is the eye, is turned off by the shielding unit 32j, and visible light to the left eye EL is shielded. At the same time, the shielding unit control unit 27f of the control unit 27 turns on the display 32a and causes the right eye ER to present the fixation target X.

  The blocking of the visible light to the left subject's eye EL by the blocking part 32j causes the eyeball of the left subject's eye EL to move. In FIG. 17B, the pupil of the left subject's eye EL moves further outward (leftward in the figure) (pupil P3 → P6). The visual axis movement detection unit 27c of the control unit 27 detects the eyeball movement of the left subject's eye EL observed at the same time as the shielding of the visible light to the left subject's eye EL, and from this eyeball movement, the eyeball movement of the left subject's eye EL is detected. Calculate the visual axis presumed to have been located before it occurred.

  In the ophthalmologic apparatus 10 according to the present embodiment, the visual axis movement detecting unit 27c calculates the visual axis of the eye E based on the amount of movement of the corneal reflection position of the eye E and / or the amount of movement of the center of the pupil. I do. The procedure for detecting the position of the corneal reflection and the position of the center of the pupil will be described later in detail.

  Then, as shown in FIG. 17B, the fixation target movement control unit 27d converts the fixation target ● presented to the left subject's eye EL into the visual axis before the eyeball movement calculated by the visual axis movement detection unit 27c. Move up (to the left in the figure). The movement of the fixation target ● by the fixation target movement control unit 27d is performed by moving and displaying the fixation target ● displayed on the display 32a of the target target projection system 32 in a predetermined direction.

  Thereafter, the shielding unit control unit 27f of the control unit 27 uses the fixation eye as shown in FIG. 17C two seconds after the shielding of the visible light to the left subject's eye EL shown in FIG. 17B. The display 32a of the optotype projection system 32 of the measurement optical system 21 that measures a certain right eye ER is turned off by the shielding unit 32j, and visible light to the right eye ER is shielded. At the same time, the shielding section control section 27f of the control section 27 turns on the display 32a to cause the left subject's eye EL to present the fixation target ●. As described above, the fixation target ● presented to the left subject's eye EL has been moved to the left in the figure as the left subject's eye EL moves.

  Then, as shown in FIGS. 18A to 18E, the shielding unit control unit 27f alternately shields the right eye ER and the left eye EL by the shielding unit 32j, and the left eye EL is shielded by the shielding unit 32j. While being blocked, the fixation target movement control unit 27d repeatedly moves the fixation target ●, and finally, as shown in FIG. 18 (e), the left subject's eye EL which is a non-fixation eye. When the eyeball movement does not occur, the movement of the fixation target ● by the fixation target movement control unit 27d is stopped, and the position of the fixation target ● is determined.

  Thereafter, as shown in FIG. 19, the visual axis calculation unit 27e obtains the amount of movement (indicated by XΔ in the figure) of the fixation target ● presented to the left subject's eye EL, and calculates the left subject's eye EL from this moving amount. Calculate the visual axis.

  In FIG. 19, the moving amount is set to XΔ because the fixation target ● moves only in the horizontal direction (X direction) in the illustrated example, and the fixation target also moves in the vertical direction (Y direction). In this case, the vertical movement amount YΔ can be obtained. Hereinafter, when the description is made without limiting the direction, it is simply indicated as the movement amount Δ.

  FIG. 6 is a horizontal sectional view when the right eye ER is viewed from above. In FIG. 6, the left side corresponds to the front and the right side corresponds to the rear. The axis connecting the fixation target (fixation point) where the right subject's eye ER is fixating and the pupil center PC is the visual axis VX indicating where the right subject's eye ER is looking. On the other hand, an axis that exits from the pupil center PC in a direction perpendicular to the cornea Ec is the pupil axis PX that indicates the direction in which the right eye ER faces. Even in the eye E to be examined without a squint, the visual axis VX is slightly shifted to the nose side (downward in FIG. 6) with respect to the pupil axis PX. The angle between the visual axis VX and the pupil axis PX is called a lambda angle (indicated by λ in the figure). Although this lambda angle has individual differences even in the normal eye E without a squint, the average value is + 5 °. It is necessary to take this lambda angle into account when performing a quantitative inspection of strabismus.

  Here, the visual axis VX of the subject's eye E can be known from the position of a bright spot image Br (hereinafter, referred to as corneal reflection Br) based on the alignment light source 36a. The pupil axis PX of the eye E can be known from the position of the pupil center PC. A detailed calculation method of the visual axis VX and the pupil axis PX will be described later.

  FIG. 8 is a diagram showing a positional relationship between the pupil P and the corneal reflex Br in various perspectives. As shown in FIG. 8, in the eye E to be examined having a perspective (the right eye ER in the example shown in FIG. 8), the position of the corneal reflection Br is shifted from the center of the pupil (hereinafter, this is referred to as pupil center PC). You can see that there is.

  As described above, in the ophthalmologic apparatus 10 according to the present embodiment, the visual axis movement detection unit 27c and the visual axis calculation unit 27e determine the movement amount of the position of the corneal reflection Br of the eye E and / or the pupil center PC. The visual axis VX of the eye E is calculated based on the amount of movement. Specifically, the pupil center detection unit 27g and the corneal reflection position detection unit 27h of the control unit 27 determine the center of the pupil image Ep in the anterior eye image E ′ of the eye E, ie, the pupil center PC and the position of the corneal reflection Br. Respectively. Then, the visual axis movement detecting unit 27c and the visual axis calculating unit 27e determine the eye to be examined based on the position of the pupil center PC and the position of the corneal reflection Br detected by the pupil center detecting unit 27g and the corneal reflection position detecting unit 27h. The pupil axis PX of E is obtained, and the visual axis VX is further obtained.

  FIG. 9 is a diagram illustrating an example of an anterior ocular segment image E ′ captured by the image sensor 31g of the observation system 31. In FIG. 9, Br indicates a corneal reflex, Ep indicates a pupil image, PC indicates a pupil center of the pupil image Ep, and Ir indicates an iris image.

  FIG. 9A is an anterior segment image E ′ of the subject's eye E, which is a fixation eye in a state where an instruction to fixate a specific viewpoint (fixation point) is given. As described above, in the case of the subject's eye E which is a fixation eye, the center of the pupil image Ep in the anterior ocular segment image E ', that is, the pupil center PC and the corneal reflection Br are at the same position.

  Next, FIG. 9B shows an anterior eye image E ′ of the eye E to be inspected, which is a non-fixed eye in a state where an instruction to fixate a specific viewpoint (fixation point) is given. The line of sight of the subject's eye E, which is a non-fixation target, does not face the fixation point. Therefore, as described above, the position of the corneal reflection Br in the anterior eye image E 'is the pupil center PC of the pupil image Ep. Deviate.

  The method of obtaining the position of the pupil center PC in the anterior eye image E ′ by the pupil center detection unit 27g may be appropriately selected from known methods. As an example, the pupil center detection unit 27g detects the edge of the pupil image Ep from the anterior eye image E ′ and calculates the boundary coordinates of the pupil image Ep. The edge of the pupil image Ep can be detected, for example, based on the difference in brightness between the pupil image Ep and the iris image Ir in the anterior eye image E ′.

Next, the pupil center detection unit 27g calculates the center of the pupil approximation ellipse by elliptically approximating the boundary coordinates of the pupil image Ep. First, the pupil center detection unit 27g obtains coefficients a, b, c, d, and h in the general formula of the ellipse shown in the following equation (2) by the least square method from the boundary coordinates of the pupil image Ep.

Then, the pupil center detection unit 27g calculates the center coordinates of the approximate pupil ellipse from the coefficient in the general formula (2) of the ellipse according to the following equation (3).
The center coordinates of the approximate pupil ellipse obtained by equation (3) are the coordinates of the pupil center PC.

  In addition, the corneal reflection position detection unit 27h obtains the position coordinates of the corneal reflection Br in the anterior ocular segment image E '. In the ophthalmologic apparatus 10 according to the present embodiment, since the alignment light source 36a is an infrared light, only the signal in the infrared light region is extracted from the output signal of the image sensor 31g, so that it is based on the reflected light from the alignment light source 36a. The position of the corneal reflection Br can be easily and accurately obtained.

Then, the visual axis movement detection unit 27c obtains the pupil axis PX based on the position of the pupil center PC and / or the position of the corneal reflection Br detected by the pupil center detection unit 27g and the corneal reflection position detection unit 27h. In addition, the visual axis calculation unit 27e forms the pupil axis PX of the eye E and the optical axis of the measurement optical system 21 from the pupil axis PX and the movement amount of the pupil center PC and / or the movement amount of the position of the corneal reflection Br. obtains the angle theta, based on lambda angle λ formed between the angle theta and pupillary axis PX and the visual axis VX, obtains the angle theta ₁ between visual axis VX and the optical axis. The angle theta ₁ is a moving amount of the visual axis VX showing the eye movement of the eye E. In this way, the visual axis calculation unit 27e verifies the visual axis VX calculated from the moving amount Δ of the fixation target based on the position of the pupil center PC and / or the position of the corneal reflection Br.

  As an example, the visual axis movement detection unit 27c and the visual axis calculation unit 27e determine the angle θ based on the position of the corneal reflection Br. The calculation procedure of the angle θ will be described with reference to FIG. FIG. 11A shows the non-fixed eye in a state in which the fixation target is fixed, and FIG. 11B shows the non-fixed eye in a state in which the eyeball moves due to blocking of visible light.

As described above, when a parallel light beam enters the eye E from the alignment light source 36a, a spot-like image (Purkinje image) is formed at the position Q inside the cornea as shown in FIG. Since the corneal curvature center R ₀ is different from the eyeball rotation point O, when the eyeball rotates at an angle θ about the eyeball rotation point O with the movement of the eyeball, the position Q of the bright spot image in the anterior eye part image E ′ becomes It moves as shown in FIG. The visual axis movement detection unit 27c and the visual axis calculation unit 27e specify the position of the corneal reflection Br in the anterior eye image E ′ of the eye E, and specify the displacement of this position as the movement amount Δ.

The distance from the corneal vertex Ept to eyeball rotation point O and L _0, if the radius of curvature of the cornea and r, the amount of movement Δ position of the corneal reflection Br, is expressed by the equation (4). From the equation (4), the angle θ can be calculated. Then, by adding the lambda angle λ to the angle theta, it can be calculated the angle theta ₁ between tooth axis VX and the optical axis.
Δ = (L ₀ −r) · sin θ (4)

The distance L ₀ from the corneal vertex to the eyeball rotation point O may be a predetermined value (for example, 13 mm is the average value). Alternatively, when the actual distance is known in measurement by another device, this value may be input. As the radius of curvature r of the cornea, an actual measurement value or an average value (7.7 mm) obtained by keratometry can be used.

  Alternatively, the visual axis movement detection unit 27c and the visual axis calculation unit 27e determine the angle θ between the pupil axis PX and the optical axis based on the position of the pupil center PC. The procedure for calculating the angle θ will be described with reference to FIG.

  When the eyeball rotates around the eyeball rotation point O along with the movement of the eyeball, the position of the pupil center PC in the anterior segment image E ′ of the eye E moves as shown in FIGS. I do. The visual axis movement detecting unit 27c and the visual axis calculating unit 27e specify the pupil region in the anterior eye image E ′ of the eye E, specify the position of the pupil center PC of the specified pupil region, and determine the positions of these positions. Is obtained as a movement amount Δ ′.

The distance from the corneal vertex Ept to eyeball rotation point O and L _0, the corneal vertex Ept and the distance to the position of the pupil center PC is N, the amount of movement of the position of the pupil center PC delta 'is the formula (5) Is represented as

Δ ′ = (L ₀ −N) · sin θ (5)

The distance L ₀ from the corneal vertex to the eyeball rotation point O may be a predetermined value (for example, 13 mm is the average value). The distance N from the corneal vertex Ept to the pupil center PC may be a predetermined value (for example, an average value of 3 to 3.6 mm). Alternatively, if the actual distance _L0 or the actual distance of the PC is known in the measurement by another device, this value may be input.

Further, as another calculation method of the angle θ, for example, the shift amount (distance d ₀ ) of the position of the corneal reflection Br with respect to the position of the pupil center PC shown in FIG. 12B and the distance from the corneal curvature center R ₀ to the pupil center PC It can be calculated by using the distance _{r 0.} The displacement amount (distance d ₀ ) is determined by the coordinates of the pupil center PC obtained by the pupil center detection unit 27g using the above equation (3) and the position of the corneal reflection Br obtained by the corneal reflection position detection unit 27h. It can be obtained based on the coordinates. The distance r ₀ is obtained by subtracting the distance N between the corneal vertex Ept and the pupil center PC from the radius of curvature r of the cornea. Assuming that the average value of r = 7.7 mm and the average value of N = 3.6 mm (however, the average value when the pupil center PC is the front surface of the crystalline lens), the distance r ₀ = (7.7-3.6). ) Mm = 4.1 mm.

Then, the visual axis calculation unit 27e, the amount of deviation d ₀ and the distance r _0, obtains an angle between the optical axis of the pupillary axis PX and the measurement optical system 21 as an angle theta. The distance d ₀ between the pupil center PC and the corneal reflection Br, the radius of curvature r of the cornea, and the angle θ between the visual axis VX and the optical axis of the measurement optical system 21 shown in FIG. It is expressed by a relational expression like 6).

sin θ = d ₀ / r ₀ (6)

The angle θ can be calculated by substituting the distance d ₀ obtained above and the distance r ₀ into the above equation (6).

Incidentally, each position of the pupil center PC and the corneal reflection Br is susceptible to refraction through the cornea, and there is individual difference in the distance r _0. Therefore, the pupil axis PX of the subject's eye E without squint and the pupil axis PX of the subject's eye E in various other directions are collected, and the distances d ₀ and r ₀ are collected, and based on these simultaneous equations, The distance r ₀ may be optimized. Alternatively, the distance r ₀ may be optimized from the measured value of the radius of curvature r of the cornea acquired by the kerato measurement.

Alternatively, based on the following equation (6-1), the radius of curvature r of the cornea (that is, the distance from the corneal curvature center _R0 to the corneal vertex Ept), and the distance d between the position of the corneal vertex Ept and the position of the corneal reflection Br May be used for the calculation.

  sin θ = d / r (6-1)

  In addition, the visual axis movement detecting unit 27c and the visual axis calculating unit 27e may specify the direction of the subject's eye by, for example, a scleral reflection method. The sclera reflection method is a method that utilizes a difference in reflectance between the cornea (black eye) and the sclera (white eye). The visual axis movement detection unit 27c and the visual axis calculation unit 27e irradiate the eye E with near-infrared light, measure the intensity of the reflected light from the eye E, specify the corneal region, and The direction of the position of the cornea region (for example, the center of the cornea) with respect to the predetermined reference position of E is specified as the direction of the eye to be examined.

  Further, the visual axis movement detecting unit 27c and the visual axis calculating unit 27e may specify the direction of the eye E by analyzing, for example, the anterior eye image E ′ of the eye E. The visual axis movement detection unit 27c and the visual axis calculation unit 27e specify a corneal region (black eye region) and a sclera region (white eye region) from the acquired luminance information in the anterior eye image E ′ of the subject's eye E, The orientation of the position of the corneal region (corneal center and pupil center in the corneal region) with respect to a predetermined reference position of the eye E is specified as the direction of the eye to be examined.

  Further, the visual axis calculation unit 27e creates a schematic diagram showing the pupil center Ep1 and the position of the corneal reflection Br in the anterior eye image E ′, and displays this on the display surface 25a of the examiner controller 25.

  FIG. 10 shows an example of a schematic diagram displayed on the display surface 25a. FIG. 10A is a diagram showing a schematic view of the eye E to be examined, in which the left eye E is an external perspective (see FIG. 8), and FIG. 10B is an actual pupil P and corneal reflection Br of the eye E. FIG. In the schematic diagram shown in FIG. 10A, the inner circle C1 indicates the edge of the pupil P, and the outer circle C2 indicates the edge of the cornea Ec. The position of the corneal reflection Br is indicated by x. The position of the corneal reflection Br of the right subject's eye ER, which is the fixation eye, substantially coincides with the center of the pupil P (pupil center PC), while the position of the corneal reflection Br of the left subject's eye EL, which is the non-fixation eye, is the pupil. It does not coincide with the center of P (pupil center PC) (it actually reaches the edge of cornea Ec).

(Operation of the ophthalmic device)
Next, an outline of the operation of the ophthalmologic apparatus 10 according to the present embodiment will be described with reference to the flowchart shown in FIG. 14 and FIG.

  The flowchart shown in FIG. 14 is for performing a strabismus examination by the ophthalmologic apparatus 10 after a strabismus is found in any of the eyes E to be examined.

  First, in Step S1, the control unit 27 rotates the measuring head 16 so that the presentation position of the fixation target is set to a predetermined position. Next, in step S2, the optotype projection system 32 displays a fixation target at the center position of the display 32a. In this state, the examiner instructs the subject to fixate the fixation target.

  In step S <b> 3, the visual axis movement detection unit 27 c sets the visual axis VX of the right eye ER and the left eye EL and the optical axis of the measurement optical system 21 in a state where the subject is fixed on the fixation target. By calculating the shift amount, the eye positions of the eye E are measured. As a result, the control unit 27 determines which of the right eye ER and the left eye EL is the non-fixed eye.

  Next, in step S4, the control unit 27 displays different fixation targets on the displays 32a of the target projection system 32 of the pair of measurement optical systems 21 to thereby provide different fixation targets for the fixation eye and the non-fixation eye. Present a target. In step S5, the shielding unit control unit 27f causes the shielding unit 32j to turn off the display 32a of the optotype projection system 32 of the measurement optical system 21 that measures the eye E, which is a non-fixed eye, and the non-fixed eye To block the visible light to the eye E to be examined.

  After a lapse of a predetermined time (for example, 2 seconds) from the occlusion of the non-fixation eye in step S5, in step S6, the shielding unit control unit 27f controls the measurement optical system 21 that measures the eye E to be the fixation eye. The display 32a of the optotype projection system 32 is turned off by the shielding unit 32j, and the visible light to the eye E, which is the fixation eye, is shielded.

  After a lapse of a predetermined time (for example, 0.5 seconds) from the occlusion of the fixation eye in step S6, in step S7, the shielding unit control unit 27f measures the measurement eye E which is the non-fixation eye E. The display 32a of the optotype projection system 32 of 21 is turned off by the shielding unit 32j, and the visible light to the subject's eye E, which is a non-fixated eye, is blocked.

  In step S8, the visual axis movement detecting unit 27c detects the eye movement of the non-fixed eye observed simultaneously with the blocking of the visible light to the non-fixed eye, and the eye movement of the non-fixed eye is detected from this eye movement. Calculate the visual axis presumed to have been located before it occurred.

  In step S9, the fixation target movement control unit 27d moves the fixation target presented to the non-fixation eye on the visual axis before the movement of the eyeball calculated by the visual axis movement detection unit 27c in step S8.

  After a lapse of a predetermined time (for example, 2 seconds) from the shielding of the non-fixed eye in step S7, in step S10, the shielding unit control unit 27f shields visible light to the eye E, which is the fixed eye. Next, after a lapse of a predetermined time (for example, 0.5 seconds) from the occlusion of the fixation eye in step S10, in step S11, the shielding unit control unit 27f shields visible light to the eye E, which is a non-fixation eye. .

  In step S12, the visual axis movement detecting unit 27c detects the eye movement of the non-fixation eye observed simultaneously with the blocking of the visible light to the non-fixation eye, and the eye movement of the non-fixation eye is determined from the eye movement. Calculate the visual axis presumed to have been located before it occurred.

  In step S13, it is determined whether the visual axis calculated in step S12 does not change from the visual axis calculated in step S8 (that is, there is no rotation of the visual axis). If there is no change in visual axis (YES in step S13), the program proceeds to step S15, and if there is a change in visual axis (NO in step S13), the program proceeds to step S14.

  In step S14, the fixation target movement control unit 27d moves the fixation target presented to the non-fixation eye on the visual axis before the eyeball movement calculated by the visual axis movement detection unit 27c in step S12. Thereafter, the program returns to step S6.

In step S15, based on the amount of movement of the fixation target by the fixation target movement control unit 27d, visual axis calculation section 27e calculates the angle theta ₁ between the optical axis of the visual axis VX measurement optical system 21, and further , The amount of movement of the fixation target is calculated as a value of a quantitative examination of strabismus, that is, a prism power.

  In step S16, based on the prism power calculated in step S16, the rotary prisms 32A and 32B of the optotype projection system 32 are driven to rotate, and the rotary prisms 32A and 32B give the prism base direction and the prism power. In this state, the examiner performs a subjective test on the examinee as to whether the fixation target presented by the optotype projection system 32 is shifted (blurred) between the right eye ER and the left eye EL. (Step S17). Thereafter, the examiner instructs the rotary driving of the rotary prisms 32A and 32B using the examiner controller 25 and the like, finely adjusts the prism base direction and the prism power given by the rotary prisms 32A and 32B, and finally, The degree of obliqueness of the right eye ER or the left eye EL in a state where the fixation target is not shifted and detected is obtained as a prism base direction and a prism power.

  FIG. 20 is a diagram showing an example of a screen displayed on the display surface 25a of the examiner controller 25 of the ophthalmologic apparatus 10 according to the present embodiment. The screen shown in FIG. 20 is displayed after calculating the amount of deviation between the visual axis VX and the optical axis of the measurement optical system performed in step S3 in the flowchart of FIG.

  The anterior eye image ER ′ of the right eye ER is displayed on the left of the center of the screen shown in FIG. 20, and the anterior eye image EL ′ of the left eye EL is displayed on the right. As described above, these anterior eye images ER ′ and EL ′ are captured by the image sensor 31 g of the observation system 31.

  In addition, below these anterior segment images ER ′ and EL ′, fixation targets 40R and 40L currently displayed by the display 32a of the target projection system 32 are displayed, respectively. Below the fixation targets 40R and 40L, schematic diagrams 41R and 41L, which are detection results of the pupil center detection unit 27g and the corneal reflection position detection unit 27h, are displayed, respectively.

(Effects of ophthalmic equipment)
In the ophthalmologic apparatus 10 according to the present embodiment configured as described above, the fixation target movement control unit 27d intersects the fixation target with the optical axis based on the movement of the visual axis detected by the visual axis movement detection unit 27c. The visual axis calculation unit 27e calculates the visual axis of the right eye or the left eye based on the amount of movement of the fixation target moved by the fixation target movement control unit 27d.

Therefore, the moving amount of the fixation target at the time when the shift of the visual axis does not occur even when the fixation target movement control unit 27d moves the fixation target corresponds to the shift amount Δ of the visual axis of the non-fixation target. Therefore, based on the amount of movement of the fixation target, the deviation amount Δ of the visual axis of the non-fixation target, and the angle θ ₁ between the visual axis of the oblique eye E and the optical axis of the measurement optical system 21. Can be calculated.

Since the shift amount Δ and the angle θ ₁ are quantitative values of the squint of the eye E, the examination of the squint and the oblique position of the eye E is automatically performed by the ophthalmologic apparatus 10 according to the present embodiment. And it can be performed precisely.

  Here, the optotype projection system 32 of the measurement optical system 21 includes a shielding unit 32j that blocks the presentation of the fixation target to the right eye ER and the left eye EL, and the shielding unit control unit 27f includes a shielding unit. 32j, the presentation of the fixation target to the right eye ER or the left subject eye EL is blocked, and after the presentation of the fixation target is blocked, the blocking of the presentation of the fixation target by the blocking unit 32j is stopped. The axis movement detecting unit 27c is configured to block at least one of the right eye ER and the left eye EL after blocking the presentation of the fixation target by the shielding unit 32j or stopping the blocking of the presentation of the fixation target by the shielding unit 32j. Is detected, the ophthalmologic apparatus 10 according to the present embodiment can perform a quantitative inspection of strabismus based on the alternating prism shielding test.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiment and the example, and a design change that does not depart from the gist of the present invention. Are included in the present invention.

  As an example, the distance between the presentation position of the fixation target and the right eye or the left eye may be displayed on the display surface 25a of the display unit 25b of the examiner controller 25 (distance L in FIG. 13). . FIG. 6 is a view showing the relationship between the visual axis and the pupil axis based on the calculation result by the visual axis calculation unit 27e on the display surface 25a. As an example, a horizontal cross section of the right eye and the left eye as shown in FIG. A diagram in which the visual axis and the pupil axis (optical axis) based on the actual measurement result may be added to the diagram may be displayed.

  Further, in the ophthalmologic apparatus 10 according to the above-described embodiment, the fixation target movement control unit 27d moves the display position of the fixation target displayed on the display 32a of the target projection system 32, and thereby the eye E to be examined. Was moved, but the method of moving the fixation target is not limited to this. As an example, the fixation target movement control unit 27d causes the drive mechanism (drive unit) 15 to rotate the measurement head 16 to move the presenting position of the fixation target in the X direction of the ophthalmologic apparatus 10 to thereby fixate the fixation target. May be moved. In addition, the fixation target movement control unit 27d gives a prism power to the fixation target presented by the display 32a by driving the rotary prisms 32A and 32B of the target projection system 32 by a drive unit (not shown). The fixation target may be moved. Naturally, the fixation target may be moved by a combination of these methods.

Br Cornea reflection E, ER, EL Eye to be inspected EL ', ER' Anterior eye image Ec Cornea Ep Pupil image P Pupil PC Pupil center PX Pupil axis R Bright point VX Visual axis Δ Shift amount 10 Ophthalmic apparatus 15 Driving mechanism (Drive unit )
16 Measuring head 21, 21R, 21L Measuring optical system 25 Examiner controller 25b Display unit 27 Control unit 27c Visual axis movement detection unit 27d Fixation target movement control unit 27e Visual axis calculation unit 27f Shield unit control unit 27g Pupil center detection unit 27h Corneal reflection position detection unit 31 Observation system 31g Image sensor (image acquisition unit)
32 target projection systems 32A, 32B rotary prism 32a display 32j shielding unit 36 alignment system 36a alignment light source

Claims (8)

A pair of measurement heads each storing a measurement optical system that acquires eye information of the right eye or the left eye of the subject,
An image acquisition unit that is provided in the measurement optical system and acquires an anterior segment image on the optical axis of the measurement optical system of the right eye and the left eye.
An optotype projection system that is provided in the measurement optical system and that presents a fixation target for causing the right eye and the left eye to fixate at least one line of sight to the right eye and the left eye. When,
From the anterior segment images of the right eye and the left eye acquired by the image acquisition unit in the state where the fixation target is presented, movement of at least one visual axis of the right eye or the left eye Visual axis movement detection unit for detecting
A fixation target movement control unit that moves the fixation target in a direction that intersects the optical axis based on the movement of the visual axis detected by the visual axis movement detection unit;
An ophthalmologic apparatus comprising: a visual axis calculation unit configured to calculate a visual axis of the right eye or the left eye based on a moving amount of the fixation target. The optotype projection system has an optotype display unit for displaying the fixation target,
The ophthalmologic apparatus includes a driving unit that rotates the measurement head around an eyeball rotation axis of the right eye and the left eye, and
The fixation target movement control unit moves the fixation target displayed on the optotype display unit on the optotype display unit and / or rotates the measurement head to thereby fix the fixation target. The ophthalmologic apparatus according to claim 1, wherein the device is moved. The optotype projection system has a rotary prism that provides a variable prism power to the fixation target displayed on the optotype display section,
The ophthalmologic apparatus according to claim 2, wherein the fixation target movement control unit moves the fixation target by changing a prism power given by the rotary prism. The measurement optical system has a shielding unit that blocks the presentation of a fixation target to the right eye and the left eye.
The ophthalmologic apparatus may block the presentation of the fixation target to the right subject's eye or the left subject's eye by the shielding unit, and may block the presentation of the fixation target after blocking the presentation of the fixation target. A shielding unit control unit for stopping shielding of the presentation of the mark,
The visual axis movement detection unit is at least one of the right eye or the left eye after shielding the presentation of the fixation target by the shielding unit, or after stopping the shielding of the presentation of the fixation target by the shielding unit. The ophthalmologic apparatus according to any one of claims 1 to 3, wherein the movement of the visual axis is detected. A pupil center detection unit that detects a pupil center of the right eye and the left eye from the anterior eye image of the right eye and the left eye obtained by the image acquisition unit,
Based on a point image obtained by forming light rays parallel to the optical axis incident on the right eye and the left eye from the measurement optical system in the right eye and the left eye, A corneal reflection position detection unit that detects the position of corneal reflection of the right eye and the left eye,
Has,
5. The ophthalmologic apparatus according to claim 1, wherein the visual axis calculation unit verifies the calculated visual axis based on the pupil center and the position of the corneal reflection.   The display device according to any one of claims 1 to 5, further comprising a display unit that displays a cross-sectional view in which the visual axis and the optical axis are displayed on a horizontal cross section of the right eye and the left eye. Ophthalmic equipment.   The display unit displays a distance between the position of the fixation target presented in front of the right eye and the left eye and the right eye or the left eye. Item 7. An ophthalmologic apparatus according to item 6.   2. The visual axis calculation unit calculates a prism base direction and a prism power of the right eye and the left eye based on the calculated visual axes of the right eye and the left eye. An ophthalmologic apparatus according to any one of claims 1 to 7.